SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc5ae2f5a211bb62b9e2b010f41fc1457308655da70b897c6188eea2ad943bab' 
  AND token = 'NuX/VHVyv5ZKsQCP88umzGhnLWj79QztdiY7waKy9Wc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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