SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '253e6c912541ad84298167a573ef10b051cb742d643f022b8cdf35c4f153f644' 
  AND token = 'q061aYD4bnIroTnsatkUUt27FkRihcXy9CgTUNJGwks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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