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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68d22141efab353ac9a0e941c6d3a3c0415784aeb9e4859385a8744cd4c22e53' 
  AND token = 'd2FR+8+Pe2Aaqi/mD7cGuEsrxqZ6prRCRXqvCTCdEMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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