SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb79f7042bca50c313a7468d0efab854c6d9a8abcf59d2efffde226fff8165bb' 
  AND token = 'kJqXtlUzMG5PaeNWLEXbNyxC/BLKBfBgSR8i90tVBKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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