SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '861a16079de0cb3ce26289b37576adc2bba75e5a1ea099a71126887f19fbd823' 
  AND token = 'noxmPQcL5eO25Kph+aaP81BfOexIbZZ3UsHTmqm9GbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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