SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4820a8b76e1ff27d05e1620edd8af2362ee5310da2fcd17d122927789dd656d8' 
  AND token = 'O/ybW8Ml6dtOqemr3QZbq4KpPRkcazZ+YZd2rGDkI54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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