SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91247d445a8ba892f2797926e9ce7c251df67969485ddb06ceb938876f438bc4' 
  AND token = 'XKVgSksENLwYtKntnBLC1JEPsBMtdTjcoKdNc7CPTWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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