SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89a0eeb301214bc614e5c690d106a807ee88810cc390dff51179f3bef49ecd6a' 
  AND token = 'f8w5dAQ+ovsgjvGtWCZRXX5cgECxhQ1N/lCAoKYjvk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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