SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74098884c8e2b821e0d93deaf73da66b3f0a6708dc8d9113ff83622ce2b7909b' 
  AND token = '+5xKg0K3GbJxVC3DSbrfYpMVGhdy+/wJ6EZyUTsdLMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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