SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '996ca29c73c3a021fbc0bd2264246dcabebf0301bd1028877b0118b04ea6ba19' 
  AND token = 'exlOpPwQBVziwTbncsyf55uc3zLeuzZSXnVzBxStqSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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