SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '986d2363f8d91285bcb3007e044a7add364bfb3dab80f5a532debd9954253d13' 
  AND token = 'xupqgJtMM3onvGqPjL0GbQho5UFqX1m4tNKHIUJ2CuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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