SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3ec516005a109978f5043e28bd8aaadf28998cc19301351eab59ff97de61842' 
  AND token = 'IIZiNsJyscdt+ZBsqxka1FCNn/emwNwTFj+EkxNwI74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}