SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55467bc2384ab20fffd19ab15b929c16535907da59b877dd2a5742d1d9e2cff9' 
  AND token = 'nIQJvBEcQ7ZglU+QABs4j5k5TIbeuDf29u/FemlUShs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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