SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8ab9413a1762c858171a6015ff2b752d5acae0028f112eba6a8346c6f92940b' 
  AND token = 'GP3szYCFjj3FgLBwU58Y5z7VSRwrRnO578ivv6YYQRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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