SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd90a106f71f413a7f708ad5bda58e77c15696f3f19796ed5cd96ae64327400bf' 
  AND token = 'caVltbYk/tnnCsrFCQEs0TvCLPxqXZFiYh4U2iv3wRI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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