SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a64e6995f88ca29bd5c8114b1cde0d1a03da1dd4c956fb80204c1af50a13ba09' 
  AND token = 'lKPrHiSKBF+NNVqbmTnf5OhnBQ7PwU4ElawUuolLD8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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