SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b238ccdd26d3e52372bb2ef6576d76622b468ce39b0e999918d6d14afc011a6a' 
  AND token = 'LUENgS7WfYzevyxK6IzYPDx03BdP8CbdtuCsozcWHuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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