SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8d4fd5e566bfe61cac1819db24a717d0f50bcaec82563627c71cf38d99e0055' 
  AND token = 'nvRRaeIdVtYFGNP4a+SvwduP3XZRiWEMZdVAce0+V3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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