SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0da4803b508bc98e9f9034e7eacf0b8a37e908d224547756afbace33d4b5492' 
  AND token = 'OyxfLVqMfE9BvaiaYeGqlxfGzf+6phvy5in9nU3xJ6s=' 
  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"
    }
  }
}