SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e8c0de51b4f06757b9f58bac360935a8f09b0d2a9c063e1409765be51738a85' 
  AND token = 'fYWcLstCz15iAiZHCotr177etd0QRWnMtCRaBaJsTbg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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