SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8df7682ac0ad359a9913ea978f1abf7f84b510c2d8132d99c527b4f4bd755414' 
  AND token = 'jLNGKRxJH7ziFRnRFZVkV9bdEeERqcCNjDzeGuyRNUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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