SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b650c5b0a7a326bf668aa2bbfdafb8bf6e220d43ed507866ee166664c5ebc6a8' 
  AND token = 'smAaXAdPQm6u2gXO4SQwepcjbkiZd2uCSO9zgkmMbd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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