SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f554b7a6d48eef223e0e453f00b5523622532b446e153003944e11f833509e2a' 
  AND token = '/9THuewPkozkXyuvwvnh7SHfLovvPIU30LohIxeOJLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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