SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7d69235b3b0afc1cd5e541583755551aff4970a049b4d176908798616f364cf' 
  AND token = 'Dyx8AXq68+HOktReuGmff/7xFKSzmSxV9Z/m2Ph1tvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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