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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7eaeefaa53e01b33b9bd96281b2b8bb2082f2c9aee8a98d228be3ca74b6d78e' 
  AND token = 'QmkEibw3Ea8FTL12duzvSn7rf2Yi93m/VMRuFmimsSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}