SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8124398c6135cb8531bc648bba190a33fc2fa0dd2be8f704365ae3a264cffec7' 
  AND token = '+Bd2no11mZDJJQfU2+kJpZTkyO/CPYzmyPa9QohDUZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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