SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50797894598c12bd6965834c43f05509acf0262e4bb0233bd043b2ceff862c90' 
  AND token = 'VEXdVJpRvyDo4pevUhC23RWNJ8aYEa2CPUy4I8k5o6o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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