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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c050b5c955ee9b42c7ac4084be9a609a321ce9b0843cd63f7f573df7593e72b' 
  AND token = 'B6n9gQvYMsvE9t7LkFcj7JrZ2Sj+jnYf0BvORn+T4cs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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