SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e35836e1769646fe23bb340656b30cac684adefcdf70636028e6392b16cb9312' 
  AND token = 'Z6HvaM5wWMj8x3sBQhGx+1XuchjWYhN9strcPblqXME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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