SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5021c5e4b96b8225671925b0a687fdd976f62e9e44c87118243a9f7970ddf43' 
  AND token = 'QYI2JN+1G8Y7K2jwK0zl2EY8aCA7mA3N2wxoZbqTji0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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