SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31274dc1b12dace1debbe1104c7c1923b4c269e70eafbabc77412db18eac4c8d' 
  AND token = '77zzOhd69QPPW85QC61zfzsonyHpxLGUoKUfYaEwuhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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