SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f6342e56e3434ba5f085fd7afb6eb0def5ca3cd749a12e938bb41e56c8853c' 
  AND token = 'UGoXRg0fiV9HyKymNBsqcbGc8jE7ZxlRqXfgVXGYY+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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