SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1487e20eced6c014956aea8f5a067e69308989b40f79072aa132b00c8aa21fa1' 
  AND token = 'JKsQlFqzfi+PoEfST09eVV/aQKWZSUhdVYHMzFuboZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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