SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f71d2bb8d9653be8cba65b05f287d273786aaa04072230a653d58052f7734e9e' 
  AND token = 'R38L1KSa/VVuY6SpVB26zcDAUOTvpeI2CtmJ5aLqF30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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