SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e6a8c2fccc4dfdf1b252e9b4ca9bbd1aa6613de2b01eee53a0aeb73029a3552' 
  AND token = 'anUCJIoktiIWbgtMH3aUeW6naBhXZwSSULUqNCJa/Zw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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