SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5790933a936e40eb70da41b43de4e8e2591c0c198b4d1773299e757621461d99' 
  AND token = 'R1ymcYYpQLhLsDlSeS3y73tCWcxMvqMTXOT0SJvDR3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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