SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '856d6763a04fa08a37cd71173f57b6ebf369ace734437ede2695f0ce9c800abe' 
  AND token = '4xKeXFyEb/IivvRS+3azLk4eNdGwH3N7ECXhsw4KKL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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