SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd791a48499ad184a88bad0a970986378d5726877d6ef532a8e57d206558fba68' 
  AND token = '+7sXaKfo1VQYnzDv2BmYQFZ9sx1xHcjBBeAp1xiQNKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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