SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '852758c5bb36139558089746d5c5ed3d47f15559ca571aefe32041cdcfa9503f' 
  AND token = 'r0mL03thdWigWQ365as6z51rrsjXpEA69DOdkVg0jmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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