SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83e6eb791f18ad5c0ccba340c201cbd7cf026cd8958b4f2e110b9482af1c52e9' 
  AND token = 'fmwDdof2CIqa6hP7n+tEznexBOW8pnsfc5Off0cKMsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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