SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd138f200d94d056ee0bb9f0aa0945d99427e7d48e1a0f95415e6b5e2ca0cd0b' 
  AND token = 'PoAqWYGQFDV8pFBEkoLF0WDjEBri0Gx2nAz2/J7uSPk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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