SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b32921f262ba857487b8b5881c16a350d0337c0b3004ca6f280b10fb90bb698' 
  AND token = '7nBtNU8p9qZjqTXNW5KKHwZnpQyyB/0QaFADGrNFt4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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