SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f14dd6052274ad344777593e6495adfabe7130e5769ed9c66b8f94645b3726a' 
  AND token = 'rCX4759+69qBLPWRyMn5ZkxlTdSAE+QcgzSvNubixI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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