SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '291de909683646088435d96d25450d9eb02d0f9c1303198f32e61aeb175b44a9' 
  AND token = '/pvL7LqH677tBYnAKbYgojIZdYPDJFEbSbHnFkPluiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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