SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '423276a1aa1b67fbe8e4eb6d6200ba617e6ee955885629c91b4e3e2884cd362c' 
  AND token = '12JRwv56j/vBja7ZpfqwWRu/8YNrJ4idB8Hu940aJCs=' 
  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"
    }
  }
}