SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd68b8243512702950fe4536f5100643fc6ff3e4cf0f40fce91a4518dba54c9ef' 
  AND token = 'a/n3uN7SzuekDDlbE/D86Eo9vizAZS1IRApRzhplkWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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