SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac6303c86ffb159930c35430e25c84511b7b45273cb46b39075c7701dc020613' 
  AND token = 'dFlPN9qfr5uJjjvzUPechoYTcpFwFDPyhtfvqhIcM4o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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