SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df3fcc35c1b6a7724817426969d70a734bdaa03b6280fbc57eb23fe124d846b7' 
  AND token = 'e2Lq9e4gRh9sZnB1eDvCKCTpfByz4PXGW2kmm3ENGrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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