SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bdb4fb33750092619d10479a24589b10560bf428e6163a9178d394f0a9353fd' 
  AND token = 'Cnz23HTj4MGE6gdjnZlm/c9LElvv+bomNSm51Er0fCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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