SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7874a5d799d521b0686e35d8c23c1c7d464c4cdefe95308abebb4820040a88e' 
  AND token = 'tqLU7bCFDrIQ9M6HGwbFUCzlTatMIODs2NlKPxPFaew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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