SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5578e721f004c727134ebcacd0e2725ceead4aa15c86cdfb67fc289caed5e211' 
  AND token = 'b6i5zArtC0uMwnJUKTR6npaOk1SPbvsjrlmlIzihMn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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