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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21075a48ee81ee1725037c25e9a771dfaf84243afb7d7352144e367264c453ef' 
  AND token = '8ZJdG2+1upd+D6Hj/YMN8OAWXxbi2jthfU2n2IbLEZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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