SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b09b14db0a4220c624933ea62365ef8dc931b04011cfe6969ba3b03c81f7f5b' 
  AND token = 'mplnag5MJuH3pz6uFs6rzxyCw9ZLX52EekavJeMfAto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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