SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3f869f72cbc4bc9e3be68f52c08854606add81ccdeec3246465992ed0d8254c' 
  AND token = 'zD7gkMjsMxFdabKbCQI8IoKqNmlFdmNW88xVzVbSGYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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