SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e515294504933fb39573237643cf6ad6cf6be03566e88955227912029ec4c4d' 
  AND token = '+YmFkBjXqR9hBiDCfiglQvFHQrsJ3ms3/anktPrPgE0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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