SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29fd08d1723f3ea4400bd46d286715a704dc488af1662ab0975dd4f082bfc75d' 
  AND token = 'r8k2i+OxxVMqNcFv0Iupf0FppWUpub9Lt5g9jb0Bwyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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