SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'accc6606c8a56abdb8913c5c8a18c382952162019cd794654546bfc74b8da034' 
  AND token = 'bgcJFGfZLFiQVUEa55pwhKNathsEwTMxbevz45+8tz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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