SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e03d3148faee6acf74bfecb0871f2f0d4925b5fdd16c125e250d0a7385e58ea' 
  AND token = 'H9A6ZqakyStrdLbUUVEifiLMdoJsdel52SpgZdqv3yo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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