SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e148d2ec4e708c493806840f8e9901f7d1cda864e9d6cff025da7d0a028be749' 
  AND token = 'STUhtMmQEEF+jp+x6itdIJwYuao5gVLePEHQYmjWjy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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