SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7bf92e3d121842a672af593ab2430d93cd4d7cbabe75365ed767e29918ae34a' 
  AND token = '4bQSfwY3OJqZNjtIPxTalvS705gNwBjNcYUCrFqLhKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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