SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c83f70bfba62f2c5b23117dfc384264a8641abc11a0969c43f0da0e2c2ed9812' 
  AND token = 'fv/LtUh9nJzwmV3iOGUQ47Cbol+yipYYoEjdGq4JqxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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