SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f7b92e40cfff44d3fbb6507ea36129fff6348ffdc979d87060b75adb781977e' 
  AND token = 'oVv+QKTJ8euSAFPMvKmygBnALuBzEf9uq6hlC+4df4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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