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SELECT 
  1 
FROM 
  vi_lock_keys 
WHERE 
  key_id = '68a0a4aaa2a2576cf2d6180a5a3b019c7e446d4a1c86fb873f3ca43d7678bd78' 
  AND token = 'HcwVplCMBXepH3EH7Qa802WHyvzUowKkxei5+LVqcSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}